ELEX 4653 Final Exam 3

Instructions:

• Answer all four (4) questions.

• You have 110 minutes to complete the exam.

• This is an open-book exam. All written material is allowed.

• No electronic devices other than a flash drive and the lab PC may be used during the exam.

• No communication with others (electronic, verbal, written or otherwise) is allowed during the exam. Violations will result in a mark of zero and disciplinary action.

• Add the Python code described below in the cells provided.

• Test your code using the menu item Cell ► Run All

• The message "Solution to question N may be correct." at the bottom of the notebook means that your answer to question N may be correct.

• When the exam time is over, save the notebook (the .ipynb file) and upload it to the appropriate dropbox on the course web site.

Question 1

The code below generates two lists (x1 and x2) of numbers. Create a list y that has the same number of values as x1 and where each element is the sum of the corresponding elements of x1 and x2. For example, if x1 is 1,3,4 and x2 is 4,5,6 then y should contain 5,8,10.

from random import randrange as rr
x1=[rr(10) for i in range(rr(4,10))]
x2=[rr(10) for i in range(len(x1))]

Question 2

The following code sets the variable d to a dictionary where the key and value are both numbers. Create a dictionary d2 containing only those entries in d where the product of the key and value are greater than 10. For example if d is {1:3, 4:7, 30:-1} then d2 should be {4:7}. Hint: d.items() is an iterator that yields (key,value) tuples for the entries in d.

import random
d=dict(zip(random.sample(range(10),10),random.sample(range(10),10)))

Question 3

Write a function called pick(l,s) that returns a list of the items in the list l that are included in the set s. The values in the returned list should be in the same order that they appear in l. For example, if l=[1,3,4,5] and s={5,2,4} the function should return [4,5].

Question 4

The ISO-8601 standard for writing dates consists of a 4-digit year, a 2-digit month and a 2-digit day, each separated by optional dashes. For example, "2017-05-18" or "19811231". Set the variable isore to a regular expression that matches an ISO date string. Hint: ?

# exam validation code; do not modify
def examcheck():
    from random import randrange as rr
    import re
    
    try:
        if not any([a-b-c for a,b,c in zip(y,x1,x2)]):
            print("Solution to question 1 may be correct.") 
    except:
        pass
        
    try:
        if all([k*v>10 for k,v in d2.items()]) and \
           all([k*d[k]<=10 for k in set(d.keys())-set(d2.keys())]):
            print("Solution to question 2 may be correct.")
    except:
        pass
        
    try:
        l=random.choices(range(10),k=15)
        s=random.sample(range(10),4)
        p=pick(l,s)
        if (set(l) & set(s)) == set(p):
            print("Solution to question 3 may be correct.")
    except:
        pass
        
    try:
        if [len(re.findall(isore,s)) for s in ['19000101', '1200-10-30', '999-99-99', '']] \
            == [1,1,0,0]:
            print("Solution to question 4 may be correct.")
    except:
        pass
   

examcheck()